Devices blowing-in oxygen through the bottoms of metallurgical converters

ABSTRACT

An arrangement for preventing hydrocarbon from forming an accumulation in the region adjacent to the outlet end of the dual tube tuyere utilized for blowing-in oxygen and a liquid hydrocarbon through the bottom of a metallurgical converter.

[451 Aug. 13,1974

[56] References Cited UNITED STATES PATENTS 3,602,435 8/1971 Primary ExaminerGerald A. Dost Attorney, Agent, or Firm-Lawrence 1. Field [57] ABSTRACT An arrangement for preventing hydrocarbon from forming an accumulation in the region adjacent to the outlet end of the dual tube tuyere utilized for blowingin oxygen and a liquid hydrocarbon through the bot- 776428 tom of a metallurgical converter.

11 Claims, 6 Drawing Figures \\\lovvx if!!! Ill l I K\-I\\ /U THROUGH THE BOTTOMS 0F METALLURGICAL CONVERTERS Camille Alphonse Courard, Angluer," Belgium [73] Assignee: Centre de Recherches Metallurgiques, Brussels, Belgium Dec. 8, 1972 Foreign Application Priority Data Dec. 8, 1971 Belgium Int. C2lc 5/48. y Field of Search 266/34 PP, 35 P 4 1 V United States Patent Courard [5 DEVICES BLOWING-IN OXYGEN [75] Inventor:

22 Filed:

21 Appl. No.: 313,382

PATENIEU-mm 3mm sum 1 or 3 FIG.

FIG. 3.

PATENIED mm 3 I974 SHEET 2 BF 3 FIG. -2.

The present invention relates to improving devices for blowing-in of oxygen through the bottom of metallurgical converters.

It is known that the refining of cast iron by blowing through the converter bottom generally does not lend itself to using pure oxygen, notably because there is corrosion of the refractory lining surrounding the tuyeres at the bottom of the converter.

In order to remedy this drawback, it has been proposed already that tuyeres be used which consist of two coaxial tubes, the oxygen being blown in through the inner tube and a protecting fluid, gaseous or liquid, and preferably of endothermal reaction, being blown through the outer tube. The results achieved by means of such tuyeres have been of practical interest and sound performance of the refractory linings surrounding those tuyeres has been observed, leading to an increase in life of converter bottoms so outfitted.

However the use of such dual tube tuyeres is also subjected to certain difficulties mainly due, on one hand, to positioning the two tubes with respect to one another, and on the other hand to the respective tube dimensions required to meet the pressures and flowrates of the fluids introduced into the converters, notably when one of those fluids is a liquid hydrocarbon.

It has been observed during certain refining operations where blowing was performed through the bottom of converters by means of dual coaxial tube tuyeres of which the inner tube served for oxygen and the outer tube for a liquid hydrocarbon, that a certain amount of hydrocarbon will remain un-burned. This quantity will tend to collect around the tuyeres and to increasingly impregnate the porous refractory substance constituting the bottom until reaching the bottom plate and ultimately spreading on the work-floor.

In order to remedy such drawbacks and the danger of such flows, an attempt has beenmade to regulate pressures and injection rates and to reduce the dimensions of the annular space for the hydrocarbon transmission, but it has been impossible to entirely eliminate the presence of liquid, unburned hydrocarbon.

The object of the present invention is an insufflation device provided with a dual, coaxial tubes tuyere which makes it possible to prevent the flow of any injected but un-burned hydrocarbon out of the converter bottom.

The present invention will be more fully understood from a consideration of the embodiments shown in the drawings in which:

FIG. 1 is an axial, longitudinal section through a blowing in device according to the invention;

FIG. 2 is a view similar to FIG. 1 showing such a device provided with a tuyere extension;

FIG. 3 is a section through the extension of FIG. 2;

FIG. 4 is a top view of the extension of FIGS. 2 and FIG. 5 is an enlarged representation of a section of a tuyere with grooves; and

FIG. 6 is a similar view showing a construction perpart (2) of the dual-coaxial tubes tuyere which is located in refractory mass (3) that makes up the converter bottom,

that said enclosure is constituted of an annular base (4) which is hollow and welded onto bottom plate (5) and of a casing (6) fastened onto said annular base (4),

that said casing (6) is filled with a well-tamped refractory substance ('7) and that the wall of the annular base (4) which makes contact with casing (6) and the wall of bottom plate (5 which touches annular base (4) are provided with at least one orifice of communication, respectively (8) and (9), so as to permit subjecting said enclosure (1) to a pressure which is meant to prevent downward hydrocarbon flow through the refractory substance (7) of casing (6).

Preferably the axis of the tubular enclosure (1) will coincide with the axis of the dual, coaxial tubes tuyere.

According to the invention, the outer wall of the casing is advantageously made of a thin metal sheet, preferably steel, with a thickness of the order of 1 mm. Such slight thickness is of advantage so there be no infiltration path into the refractory substance of the converter bottom if said sheet should melt.

The outer diameter of the casing preferably will be within three and six times that of the outer tube of the tuyere.

Also according to the invention, the refractory substance filling the space between the outer casing wall and the outer tube of the dual tuyere preferably is the same as that constituting the converter bottom.

In case the protecting fluid injected by means of the outer tube of the dual tuyere is a liquid hydrocarbon, the clearance between the two tubes ordinarily must be fairly slight while still sufficient to provide the desired flow-rate as determined by practice. According to the invention, it has been found to be advantageous that the clearance between the two coaxial tubes be equal to that allowing insertion of the inner tube into the outer one in the presence of slight friction.

In order to achieve proper hydrocarbon injection rates, dual tuyere construction is advantageously executed in the following manner and according to the particular situation:

either the outer wall of the inner tube and/or the inner wall of the outer tube are provided with suitable longitudinal or helical grooves 20,

or the outer wall of the inner tube comprises several uniformly distributed zones 22 along which takes place the slight friction with respect to the outer tube, these zones being separated by flattened rectilinear areas 21.

It is known that after a certain number of refining operations have been carried out by means of a converter with dual-tuyeres equipped bottom, certain numbers of those tuyeres will have to be replaced or repaired. Generally, it is enough if the inner tube is replaced, and tuyere assembly on the bottom plate is so designed that this inner tube may be easily withdrawn and inserted again. However, if the clearance between the coaxial tubes is equal to that allowing insertion of the inner tube into the outer one in the presence of slight friction,-it will be practically impossible to remove the inner tube as experience has shown on account of thermal expansion rigidly fastening it to the outer one.

In such a case and according to the embodiment shown by way of illustration in FIGS. 2 and 3, the blow ing-in device will further comprise:

a. a tuyere-support fastened to the lower side of the bottom plate (5) of the converter at the position provided for the tuyere,

b. an annular flange (12) fastened to the outer connection (13) from the tuyere to the injection-fluids supply ductings 19,

c. at least four pressure-screws (14) passing through threaded supports in annular flange (l2) and coming to a stop against tuyere-support (10), so that the tuyere will be subjected to a force from those screws which will further the removal of the two coax ial tubes together.

In order to permit guiding the tuyeres outer tube when being positioned at the location provided at the bottom, the insufflation device advantageously will comprise a refractory-substance channel (16) resting on bottom plate (5) and the axis of which coincides with that of the injection tuyere, the inner diameter of this channel being such as to allow high-friction insertion of the said tuyeres outer tube at the center.

1 claim:

1. A device for blowing-in through the bottom of a metallurgical converter, provided with a dual, coaxial tubes tuyere of which the inner tube serves for oxygen and the outer tube for a liquid protecting fluid, for instance a hydrocarbon, thus characterized that, it comprises a tubular enclosure (1) surrounding along its entire height that part (2) of the dual, coaxial tubes tuyere which is located in the refractory mass (3) forming the converter bottom,

that said enclosure is constituted of an annular base (4) which is hollow and welded onto bottom plate (5) and of a casing (6) fastend on said annular base that said casing (6) is filled with a refractory substance (7) which is well tamped, and that the wall of annular base (4) touching casing (6) and the wall of bottom plate (5) touching annular base (4) are provided with at least one orifice of communication each, resp. (8) and (9), so as to allow subjecting said enclosure (1) to a pressure meant to prevent downward hydrocarbon flow through refractory substance (7) of casing (6).

2. A device according to claim 1, thus characterized that the axis of the tubular enclosure (1) coincides with the axis of the dual, coaxial tubes tuyere.

3. A device according to claim 1, thus characterized that the outer casing wall is constituted by a thin metal sheet.

4. A device according to claim 3, thus characterized that the metal sheet is of steel.

5. A device according to claim 3, thus characterized that the thickness of the metal sheet is of the order of 1 mm.

6. A device according to claim 1, thus characterized that the refractory substance filling the space between the outer casing wall and the dual tuyeres outer wall is the same as constituting the converter bottom.

7. A device according to claim 1, thus characterized that the clearance between the two coaxial tubes is equal to that permitting slight-friction insertion of the inner tube into the outer tube. v

8. A device according to claim 1 wherein at least one tube surface in the space between the inner tube and the outer tube is provided with grooves.

9. A device according to claim 7, thus characterized that the outer wall of the inner tube comprises several uniformly distributed zones along which takes place the slight friction with respect to the outer tube, these zones being separated by flattened rectilinear areas.

10. A device according to claim 1, thus characterized that it further comprises:

a. A tuyere-support (l0) fastened to the lower side (11) of bottom plate (5) of the converter at the proper tuyere emplacement,

b. an annular flange (12) fastened to the outer joint (13) from the tuyere to the injection fluids supply channels,

c. at least four pressure-screws (14) passing through threaded supports (15) in the annular flange (12) and coming to a stop against the tuyere-support (10) so that said tuyere is subjected to a force from those screws which is meant to remove the two coaxial tubes together.

11. A device according to claim 10, thus characterized that it comprises a refractory substance channel (16) resting on the bottom plate (5) and the axis of which coincides with that of the injection tuyere, the channel inner diameter being such as to permit highfriction insertion of the outer tube into said tuyeres inner part. 

1. A device for blowing-in through the bottom of a metallurgical converter, provided with a dual, coaxial tubes tuyere of which the inner tube serves for oxygen and the outer tube for a liquid protecting fluid, for instance a hydrocarbon, thus characterized that, it comprises a tubular enclosure (1) surrounding along its entire height that part (2) of the dual, coaxial tubes tuyere which is located in the refractory mass (3) forming the converter bottom, that said enclosure is constituted of an annular base (4) which is hollow and welded onto bottom plate (5) and of a casing (6) fastend on said annular base (4), that said casing (6) is filled with a refractory substance (7) which is well tamped, and that the wall of annular base (4) touching casing (6) and the wall of bottom plate (5) touching annular base (4) are provided with at least one orifice of communication each, resp. (8) and (9), so as to allow subjecting said enclosure (1) to a pressure meant to prevent downward hydrocarbon flow through refractory substance (7) of casing (6).
 2. A device according to claim 1, thus characterized that the axis of the tubular enclosure (1) coincides with the axis of the dual, coaxial tubes tuyere.
 3. A device according to claim 1, thus characterized that the outer casing wall is constituted by a thin metal sheet.
 4. A device according to claim 3, thus characterized that the metal sheet is of steel.
 5. A device according to claim 3, thus characterized that the thickness of the metal sheet is of the order of 1 mm.
 6. A device according to claim 1, thus characterized that the refractory substance filling the space between the outer casing wall and the dual tuyere''s outer wall is the same as constituting the converter bottom.
 7. A device according to claim 1, thus characterized that the clearance between the two coaxial tubes is equal to that permitting slight-friction insertion of the inner tube into the outer tube.
 8. A device according to claim 1 wherein at least one tube surface in the space between the inner tube and the outer tube is provided with grooves.
 9. A device according to claim 7, thus characterized that the outer wall of the inner tube comprises several uniformly distributed zones along which takes place the slight friction with respect to the outer tube, these zones being separated by flattened rectilinear areas.
 10. A device according to claim 1, thus characterized that it further comprises: a. A tuyere-support (10) fastened to the lower side (11) of bottom plate (5) of the converter at the proper tuyere emplacement, b. an annular flange (12) fastened to the outer joint (13) from the tuyere to the injection fluids supply channels, c. at least four pressure-screws (14) passing through threaded supports (15) in the annular flange (12) and coming to a stop against the tuyere-support (10) so that said tuyere is subjected to a force from those screws which is meant to remove the two coaxial tubes together.
 11. A device according to claim 10, thus characterized that it comprises a refractory substance channel (16) resting on the bottom plate (5) and the axis of which coincides with that of the injection tuyere, the channel inner diameter being such as to permit high-friction insertion of the outer tube into said tuyere''s inner part. 